Optical recording media have spread widely generally because of their superiority, such as high recording capacity and non-contact write/read system. Recordable optical disks, such as WORMs, CD-Rs, and DVD±Rs, record information by irradiating a very small area of the optical recording layer with a focused laser beam to change the properties of the irradiated area and reproduce the recorded information making use of the difference in reflected light quantity between the recorded and non-recorded areas.
Wavelengths of semiconductor lasers used in writing and reading information on the currently available optical disks of the type described are in the ranges of 750 to 830 nm for CD-Rs and of 620 to 690 nm for DVD-Rs. In pursuit of a further increased capacity, optical disks using shorter wavelength lasers have been under study. For example, those using a write wavelength of 380 to 420 nm have been studied.
Various kinds of compounds are used to form an optical recording layer of optical recording media for short wavelength lasers. For example, Patent Document 1 reports an optical recording medium containing a metallocene derivative having an indolenine skeleton as a light stabilizer or pit controlling agent; and Patent Document 2, Patent Document 3, and Patent Document 4 disclose optical recording media containing a cyanine compound having a specific structure. These compounds, however, are not always good for use as an optical recording material forming an optical recording layer in view of their absorption wavelength characteristics or solubility in a solvent used to form an optical recording layer.    Patent Document 1: JP 2001-47740A    Patent Document 2: JP 2001-301333A    Patent Document 3: JP 2004-98542A    Patent Document 4: JP 2006-150841A